It is known to provide false-twist devices of the aforedescribed type which operate in accordance with the principles of most false-twist systems, i.e. by frictionally engaging a yarn between two or more moving surfaces thereby imparting a twist in one or another direction to the yarn as it is drawn through the device.
In false-twist devices of the type with which the present invention is most concerned, three spaced-apart mutually parallel spindles are disposed with their axes at the vertices of a triangle, the spindles each carrying a number of axially spaced friction discs which interdigitate and overlap at least in a central region between these axes through which the yarn is passed so that the yarn is frictionally engaged by the discs or wheels and receives a false twist of the S-type or the Z-type(see especially application Ser. No. 200,552 and German open application 2,943,279).
The spindles are driven by at least one belt drive and thus each carries at least one friction disc so that the friction discs at least in the operative position overlap and the axes or centers of the spindles lie at the vertices of a triangle, especially an equilateral triangle.
As described in German open application 2,339,416, at least one of the spindles should be swingable relative to the others so that its disc can be brought out of its overlapping relationship with at least one other of the discs.
The swinging movement of one of the spindles and the disc or discs carried thereby is important because it permits the yarn to be fed into the assembly or removed therefrom.
In practice, it is found to be important to continue to drive the swung spindle and its discs, i.e. to continue to rotate the latter even after it has been swung from the closed position to the open position for receiving or removing the yarn. If the swingable spindle is pivotally mounted so as to swing about the axis of one of the other spindles, the interaxial spacing of these two spindles remains constant and hence a belt coupling these two spindles for driving the swingable spindle, can continue to rotate the latter in the open position without difficulty and without complex means for maintaining belt tension because the sheaves over which the belt passes are spaced at a constant distance from one another.
However, it has now been found that the swingable mounting of one spindle at the axis of another spindle is a disadvantage since the size of the unit must be increased in the axial direction to provide for journaling of arms or the like carrying the swingable spindle at the axis of the stationary spindle with which the swingable spindle is connected by the belt.
Especially with a false-twist device of small friction disc diameter this can be highly disadvantageous because in the region of the spindle bearings there is only a limited amount of space or there may not be any space at which journaling of the arms carrying the swingable spindle can be provided.
In practice, the temperature in the region of the bearings tends to increase inordinately when the pivots for the swingable spindle and discs are provided coaxially or in axial alignment with the rotational axis of the stationary spindle and disc assembly; vibrations or oscillations tend to develop which can cause undesired opening of the device and, in general, the operation of the device has not been found to be fully satisfactory.